#include <stdbool.h>
#include <stdio.h>

int main(void)
{
    bool digit_seen[10] = {false},
         repeated[10] = {false};
    int digit, i;
    long n;

    printf("Enter a number: ");
    scanf("%ld", &n);

    while (n > 0)
    {
        digit = n % 10;
        if (digit_seen[digit])
            repeated[digit] = true;
        digit_seen[digit] = true;
        n /= 10;
    }

    printf("Repeated digit(s): ");

    for (i = 0; i < 10; i++)
    {
        if (repeated[i])
            printf("%d", i);    
    }

    printf("\n");

    return 0;
}